Method for assignment of input port numbers in 3-dimension Banyan switching network of asynchronous transfer mode

ABSTRACT

Input port numbers are assigned so as to allow formation of a unit switch having a given scale of module characteristic for a 3-dimensional installation of a switching network in an asynchronous transfer mode on basis of the Banyan network. A multiplicity of unit switches of a small (n×n) scale, positioned in a front portion of the switching network, are partitioned in front unit switches. A multiplicity of unit switches of the same small (n×n) scale, positioned in a rear portion of the switching network, are partitioned in rear unit switches. Output ports of the front unit switches are coupled in sequence in a crossed manner to input ports of the rear unit switches. Further, the input port numbers of said front unit switches are reassigned in accordance with a given formula, and the output port numbers of said rear unit switches are assigned in sequence from the uppermost position to the lowermost position.

CLAIM OF PRIORITY

This application makes reference to, incorporates the same herein, andclaims all benefits accruing under 35 U.S.C § 119 from an applicationentitled Method for Assignment of Input Port Numbers in 3-dimensionBanyan Switching Network of Asynchronous Transfer Mode earlier filed inthe Korean Industrial Property Office on Dec. 26, 1995, and there dulyassigned Serial No. 56579/1995 by that Office.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for formation of a switchingnetwork in an asynchronous transfer mode (ATM) on basis of a "Banyan"network. More particularly, the present invention relates to a methodfor assignment of input port numbers, so as to be capable of3-dimensional installation of the switching network.

2. Description of the Related Art

Recently, switching networks based on the Banyan network come into wideuse for the asynchronous transfer mode (ATM) switching networks. An ATMswitching network generally requires transmission capability of at leasthundreds of megabits per second (Mb/s) of transmission speed per portand a larger scale switching network for such high transmission speed.However, as noted in the art, various limitations in some hardwarefactors exist in areas such as reception of circuit components in aprinted circuit board and its size. A fiber of connector pins and anumber of connections in a printed circuit board (PCB), transmissionspeed per link, etc. would be quite difficult in developing to a largerscale of Banyan switching network.

On this matter, among the exemplars of a contemporary practice are White(U.S. Pat. No. 5,546,540, Automatic Topology Monitor For Multi-SegmentLocal Area Network, Aug. 13, 1996) discussing an automatic topologymonitor for multi-segment local area network, which includes segmentmonitor nodes which report the presence of new end nodes to a networkmanager node. Dobbins et al. U.S. Pat. No. 5,509,123, DistributedAutonomous Object Architectures For Network Layer Routing, Apr. 16,1996) discusses an object-oriented architecture for network layerrouting which distributes function and system behavior into automomousrouter objects. Christensen et al. (U.S. Pat. No. 5,491,687, Method AndSystem In A Local Area Network Switch For Dynamically Changing OperatingModes, Feb. 13, 1996) discusses a local area network (LAN) switch havingmeans for switching modes of operation in response to a rate at whichframes having an error pass through such a LAN switch. Judd et al. (U.S.Pat. No. 5,465,251, Network Addressing, Nov. 7, 1995) discusses anetwork addressing scheme in which a message sent from a source node toa destination node includes a path address which defines the path overwhich the message should travel to reach the destination node. Norizukiet al. (U.S. Pat. No. 5,357,510, Apparatus And A Method For SupervisingAnd Controlling ATM Traffic, Oct. 18, 1994) discusses an apparatus forsupervising and controlling asynchronous transfer mode (ATM) traffic,and which collects traffic information. The apparatus comprises a celldetecting unit, an idle cell detecting unit, a cell counting unit, anidle cell counting unit, an idle cell rate detecting unit, and a controlunit. From my study of these exemplars and of the prior art, I believethat there is a need for a more effective and improved method forformation of a switching network in an asynchronous transfer mode (ATM)on basis of a "Banyan" network, as in the present invention.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide animproved method for formation of a switching network in an asynchronoustransfer mode (ATM) on basis of a "Banyan" network.

Another object of the present invention is to provide an improved methodfor assignment of input port numbers, so as to be capable of3-dimensional installation of the switching network.

Another object of the present invention is to provide a method forassignment of input port numbers so as to allow formation of a unitswitch having a predetermined scale of module characteristic for a3-dimensional installation of a switching network in an asynchronoustransfer mode (ATM) on basis of the "Banyan" network.

The above and other objects can be achieved according to the presentinvention which provides a method for formation of a 3-dimensionalasynchronous transfer mode switching network of a large (N×N) scale. Amultiplicity of unit switches of a small (n×n) scale, positioned in afront portion of the switching network, are partitioned as front unitswitches. A multiplicity of unit switches of the same small (n×n) scale,positioned in a rear portion of the switching network, are partitionedas rear unit switches. Output ports of the front unit switches arecoupled in sequence in a crossed manner to input ports of the rear unitswitches. The input port numbers of the front unit switches arere-assigned in accordance with a given formula. The output port numbersof said rear unit switches are assigned in sequence from the uppermostposition to the lowermost position.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention, and many of the attendantadvantages thereof, will be readily apparent as the same becomes betterunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings in which likereference symbols indicate the same or similar components, wherein:

FIG. 1 is a front view of a so-called book shelf type of switchingnetwork apparatus;

FIG. 2 is a rear view of the switching network apparatus of FIG. 1,illustrating a shape of electrical connection of signal lines;

FIG. 3 is a schematic diagram illustrating the construction of a unitswitch with an a×a scale of Banyan network constituted according to theprinciples of The present invention;

FIG. 4 is a schematic diagram illustrating the construction of an ATMswitching network with an N×N scale of Banyan network constructedaccording to the principles of the present invention;

FIG. 5 is a schematic diagram illustrating the construction of a3-dimensional switch with an N×N scale of Banyan network constructedaccording to the principles of the present invention;

FIG. 6 is a schematic diagram illustrating the construction of an outputport number table with 1,024×1,024 scale of Banyan network constructedwith the 3-dimensional switch installation, in which table the outputport numbers are re-allocated, and the table and the network beingconstructed according to the principles of the present invention;

FIG. 7 is a schematic diagram illustrating the construction of an inputport number table with 1,024×1,024 scale of Banyan network constitutedaccording to the 3-dimensional switch installation, in which the inputport numbers of the table are allocated according to the principles ofthe present invention; and

FIG. 8 is a schematic diagram illustrating the construction of the1,024×1,024 scale of Banyan network constructed by the 3-dimensionalswitch installation in accordance with the output port number table ofFIG. 6 and the input port number table of FIG. 7, the contruction beingaccording to the principles of the present invention.

DETAILED DESCRIPTION OF TIM PREFERRED EMBODIMENT

According to a contemporary practice, a large scale of ATM switchingnetwork based on the Banyan network is provided with a multiplicity ofprinted circuit board which are installed in a book shelf form, asillustrated in FIGS. 1 and 2. FIG. 1 shows a front view of a PCB self ofthe switching network and FIG. 2 shows a rear view of the PCB shelf withits electrical connections exposed--and further through, one or more PCBpatterns in its backboard, a unit printed circuit board constituting dieoverall switching network, are connected to each other.

The following disadvantages are noted in installing the plurality ofPCBs in the book shelf form constituting a switching network in a largescale of ATM switching network which requires a very high speed ofsignal transmission.

First, as the number of links to be connected between the PCBs in thelarge scale of ATM switching network are greatly increased, it will bedifficult for a known existing hardware environment to be adapted to usefor installation of PCBs because the number of connector pins used inthe PCBs is normally limited, thereby restricting the number of linkscapable of connection between the PCBs. Although this drawback may beavoided by enlarging die size of PCBs in backboards of the switchingnetwork and using more connectors therein, such would often cause thePCBs to bend over their frames due to the excessive weight which mayexercise an adverse effect on the structural stability of PCBs.

Next, in the book shelf form of switching network apparatus, as the PCBsare installed one after another, one by one, in order of theirsequential numbers, the farther a PCB is positioned from the first one,the longer a length of the linkage for connection with the PCB becomes.Hence, as the transmission speed per port in the ATM switching networkreaches hundreds of Mb/s, such a difference between linkage lengths forconnection with other PCBs causes an adverse generation of a delayvariation or a jitter in signal transmission. The delay variation hasthe important influence on the high speed transmission of the ATM andother synchronous switching networks. Furthermore, as such a book shelfform of switching network apparatus also tends to have a limitation onthe effective transmission distance in the high speed transmission ofthe ATM switching network, a connection in between those PCBs spacedfarther apart from each other, as shown in FIG. 3, would result inconsiderable attenuation of a transmitted signal to thereby lead to afailure of normal transmission. For instance, when the transmissionspeed per bit in application of 160 Mb/s signal transmission is 6.25E-9,a transmission distance capable of transmission without such asignificant attenuation of signal through the PCB patterns in the ATMswitching network is a few of centimeters (at the maximum). Therefore,the lengths of connections greatly affect the occurrence of signalattenuation--the better transmission reliability of the ATM switchingnetwork.

The present invention may use a unit switch with n×n scale constitutedby means of a 3-dimensional arrangement. This can solve one or more ofthe aforementioned problems caused in application of a large scale ofBanyan network with N×N size, wherein a number `n` denotes a number ofinput/output ports for a unit switch and a number "N" denotes a numberof input/output ports for a switching network. FIG. 3 is a schematicdiagram illustrating the construction of a unit switch, with n×n scale,of the switching network according to the present invention. FIG. 4 is aschematic diagram illustrating the construction of the ATM switchingnetwork with N×N scale of Banyan network constituted according to theprinciples of the present invention.

In FIG. 5, there is shown a detailed construction of the 3-dimensionalarrangement of switching network based upon the N×N scale of Banyannetwork constituted as shown in FIG. 4. This 3-dimensional arrangementof switching network is developed by dividing a large N×N scale ofswitching network into a plurality of small modules of n×n size,positioning these modules in both a front side and a rear side: of itsbackboard in a perpendicular direction with respect to each other, anddirectly connecting through connectors on the backboard to each otherwhere applicable.

However, in a situation where the n×n scale of unit switches are adaptedto be coupled to each other in under to form a 3-dimensional switchingnetwork on basis of the Banyan network, a shuffle relation within theswitching network should be considered. That is, in a situation wherethe n×n scale of unit switches in the 3-dimensional arrangement are usedto from the N×N Banyan network, the resultant switching network would beunable to provide the original characteristic of the Banyan networkitself because the positions of connection linkages between the unitswitches positioned in a front side of the backboard and thecorresponding unit switches positioned in a rear side of the backboardare changed in a certain amount. Accordingly, In order to keep thecharacteristic of the Banyan network as it was, a reshuffling in theswitching network has to be made in its input or output link.

Accordingly, the invention provides a method for reshuffling the inputlink so as to keep the characteristic of the Banyan network withoutchange, even in a situation where the n×n scale of unit switches in the3-dimensional arrangement are used to form the N×N Banyan switchingnetwork. Also, the reshuffling of input link should be performed for theinput links of all the unit switches, with this particular rule taken,because the unit switches in both the front side and the rear side ofthe back-board are coupled together in this particular form in the3-dimensional arrangement.

The invention provides a method for reshuffling the input ports to beadjusted when making the large scale of switching network based upon theBanyan network into the n×n scale of unit switch modules andconstructing the 3-dimensional arrangement of entire switching networkby using the unit switch modules. To modularize the entire switchingnetwork into a multiplicity of n×n scale of unit switches requirespartitioning of switches due to the limitation of a number of circuitcomponents receivable within a PCB or semiconductor device according tothe various hardware conditions. Here, the unit switches should have themodularity because the entire switching network can be constructed byutilizing a plurality of identical unit switches with such modularity.Thus, the switching network could be manufactured with one kind of unitswitch. However, in a situation that the unit switches are split intosmaller modules without the modularity taken into account, several kindsof small switches will have to be utilized in construction of the entireswitching network.

After manufacturing the aforementioned n×n size of unit switches, the3-dimensional arrangement system is used to construct the entireswitching network with these unit switches, in which system overcomesthe drawbacks resulted from the prior book shelf type arrangement ofprinted circuit board. Thus, as the link connection between the unitswitches is made not through a connection via its electrical signal lineas done in the book shelf type, but directly through the connector inthe backboard, there is no need to connect the N number of signal linksto the electrical signal in the backboard. Hence, in case of N×Nswitching network, the numbers of the input links, output links andconnection links between the unit switches are all "N", respectively.Therefore, the delay variation in signal transmission will not occur inthe links used for connection between the unit switches; it may resultin prevention of the signal attenuation.

However, in case where the n×n scale of unit switches are adapted to becoupled to each other in order to form a 3-dimensional switching networkon basis of the Banyan network, the resultant switching network would beunable to provide the original characteristic or the Banyan networkitself because the positions of connection linkages between the unitswitches positioned in a front side of the backboard and thecorresponding unit switches positioned in a rear side of the backboardare changed in a certain amount. Accordingly, n order to keep thecharacteristic of the Banyan network as it was, a reshuffling in theswitching network has to be made in its input or output link.

The invention therefore provides a method for reshuffling the input linkso as to keep the characteristic of the Banyan network without change incase where the n×n scale of unit switches in the 3-dimensional crossarrangement are used to form the N×N Banyan switching networks.Referring to the following table, there is shown a method forcalculating the input port numbers in accordance with the unit switch.In the table, values in each row correspond to the input port numbers ofthe unit switches, wherein the first row denotes an input port numberfor the uppermost unit switch installed onto a front side of thebackboard, and then likewise, an "n"th row denotes an input port numberfor the "n"th unit switch installed onto a front side of the backboard.In the input port numbers for unit switches, the uppermost port startsfrom "0" of the corresponding row, that is, where j=0, in the belowtable.

According to the table, the position (I, J) of each element can berepresented in an n×n matrix defined by variables `i` and "j", asfollows:

Position (i, j), where

    i (0,1,2,3 . . . n-1)

    j (0,1,2,3 . . . n-1)

wherein "n" denotes a size of the n×n square matrix, "i" a row numberand "j" a column number.

                  TABLE    ______________________________________    i/j  n-1      n-2      n-3    . . . 2                                         1     0    ______________________________________    0    0,n-1    0,n-2    0,n-3  . . . 0,2                                         0,1   0,0    1    1,n-1    1,n-2    1,n-3  . . . 1,2                                         1,1   1,0    2    2,n-1    2,n-2    2,n-3  . . . 2,2                                         2,1   2,0    3    3,n-1    3,n-2    3,n-3  . . . 3,2                                         3,1   3,0    "    "        "        "    "    "        "        "    n-2  n-2,n-1  n-2,n-2  n-2,n-3                                  . . . n-2,2                                         n-2,1 n-2,0    n-1  n-1,n-1  n-1,n-2  n-1,n-3                                  . . . n 1,2                                         n-1,1 n-1,0    ______________________________________

In the above table, a value of the element (i,j) is obtained by thefollowing formula: (i,j)=Xn+Y, wherein Xn={ j!quo2+n/2 j!mod2) and Y=(i!quo2+n/2 i!mod2) and wherein " i!quo2" denotes the quotient of "i"divided by 2 and " i!mod2" denotes the remainder of "i" divided by 2,while " j!quo" denotes the quotient of "j" divided by 2 and " j!mod2"denotes the remainder of "j" divided by 2.

Now, in order to ascertain the result of the above calculation accordingto the table, a preferred embodiment will be explained in which a1,024×1,024 scale of Banyan based switching network is constructed inthe 3-dimensional arrangement system, by using a 32×32 scale of unitswitches. FIG. 8 illustrates the construction of the 1,024×1,024 scaleof Banyan network constituted by the 3-dimensional switch installationon basis of the output port number table of FIG. 6 and the input portnumber table of FIG. 7 according to the principles of the presentinvention. In FIG. 8, the input port numbers of the unit switches, whichembodies the 32×32 scale of Banyan network in a single PCB, positionedin the front side of the backboard are calculated as in FIG. 6 on basisof the above table. FIG. 6 illustrates the construction of an outputport number table with 1,024×1,024 scale of Banyan networkconstituted--according to the 3-dimensional switch installation, inwhich table the output port numbers are reallocated according to theprinciples of the present invention. Further, the output port numbers ofthe unit switches positioned in the rear side of the backboard startfrom the rightmost unit switch taken from the rear side, and the outputport numbers in each unit switch are given in sequence downwardly from,the upper side to the lower side.

FIG. 7 illustrates the construction of an input port number table with1,024×1,024 scale of Banyan network constituted according to the3-dimensional switch installation, in which the input port numbers areallocated according to the principles of the present invention.Therefore, when the 1,024×1,024 scale of switching network isconstructed in the 3-dimensional arrangement system as shown in FIG. 8,the input port allocation of the unit switches in the front side istakes the reshuffling as seen in FIG. 7. In this occasion, theconstruction of the 1,024×1,024 scale of 3-dimensional switching networkis carried out as shown in FIG. 8.

As stated hereinbefore, the present invention re-assigns the input portnumbers in order to embody the 3-dimensional ATM switching network--forinstance, in the 3-dimensional large (N×N) scale of Banyan networkdeveloped by using a small modularized (n×n scale) unit switch. Thecharacteristic of the original Banyan network can be maintained, as itwas, by taking the reshuffling of its input port numbers, enjoying theadvantages of the 3-dimensional Banyan network.

Although the present invention has been described with reference to thepreferred embodiments thereof, those skilled in the art will readilyappreciate that various substitutions and modifications can be madethereto without departing from the spirit and scope of the invention asset forth in the appended claims.

What is claimed is:
 1. A method for formation of a 3-dimensionalasynchronous transfer mode switching network having N input ports and Noutput ports, comprising the steps of:positioning a first plurality ofunit switches of an n×n scale in a front portion of the switchingnetwork, wherein each unit switch of said first plurality of unitswitches has n input ports and n out ports; partitioning said firstplurality of unit switches in front unit switches; positioning a secondplurality of unit switches in a rear portion of the switching network,wherein each unit switch of said second plurality of unit switches has ninput ports and n output ports; partitioning said second plurality ofunit switches in rear unit switches; coupling said n output ports of thefront unit switches, in sequence and in a crossed manner, to said ninput ports of the rear unit switches; assigning output port numbers ofsaid rear unit switches in sequence from an uppermost position to alowermost position; and reassigning input port numbers of said frontunit switches in accordance with following formula:(i,j)=Xn+Y, whereinXn={jquo2+n/{2{jmod2}}}, and Y={iquo2+n/{2{imod2}}}, and i correspondsto a number of row, and j corresponds to a number of column, and wherein"iquo2" denotes the quotient of "i" divided by 2, and "imod2" denotesthe remainder of "i" divided by 2, and "jquo2" denotes the quotient of"j" divided by 2, and "jmod2" denotes the remainder of "j" divided by 2.2. The method of claim 1 wherein N is greater than n.
 3. The method ofclaim 1, wherein N is equal to n multiplied by N.
 4. A switching networkhaving N input ports and N output ports, comprising:a first plurality ofunit switches positioned in a front portion of the switching network,said first plurality of unit switches used in partitioning as front unitswitches, wherein each unit switch of said first plurality of unitswitches has n input ports and n output ports; a second plurality ofunit switches positioned in a rear portion of the switching network,said second plurality of unit switches used in partitioning as rear unitswitches, wherein each unit switch of said second plurality of unitswitches has n input ports and n output ports; said n output ports ofsaid front unit switches coupled, in sequence and in a crossed manner,to said n input ports of said rear unit switches, wherein each of said ninput ports of said front unit switches are assigned an input portnumber and each of said n output ports of said rear unit switches areassigned an output port number; wherein the input port numbers of saidfront unit switches are reassigned in accordance with the followingformula, and the output port numbers of said rear unit switches areassigned in sequence from the uppermost position to the lowermostposition;(i,j)=Xn+Y, wherein Xn={jquo2+n/{2{imod2}}}, andY={iquo2+n/{2{imod2}}}, and i corresponds to a number of row, and jcorresponds to a number of column, and "iquo2" denotes the quotient of"i" divided by 2, and "imod2" denotes the remainder of "i" divided by 2,and "jquo2" denotes the quotient of "j" divided by 2, and "jmod2"denotes the remainder of "j" divided by
 2. 5. The network of claim 4,with the network being in an asynchronous transfer mode on basis of aBanyan network.
 6. The network of claim 4, wherein N is greater than n.7. The network of claim 4, wherein N is equal to n multiplied by n. 8.The network of claim 4, wherein the network is of three dimensionalstructure.
 9. The network of claim 4, wherein said first plurality ofunit switches is a module within said switching network.
 10. The networkof claim 4, wherein said first plurality of unit switches is a modulewithin said switching network.
 11. The network of claim 4, wherein Ncorresponds to
 1024. 12. The network of claim 4, wherein n correspondsto
 32. 13. A method of forming a switching network having N input portsand N output ports, comprising the steps of:positioning a firstplurality of unit switches at a front portion of the switching network;partitioning by using said first plurality of unit switches as frontunit switches; positioning a second plurality of unit switches at a rearportion of the switching network; partitioning by using said secondplurality of unit switches as rear unit switches; placing a plurality ofn input ports and n output ports in each one of the front unit switches;placing a plurality of n input ports and n output ports in each one ofthe rear unit switches; coupling said n output ports of said front unitswitches, in sequence and in a crossed manner, to said n input ports ofsaid rear unit switches, wherein each of said n output ports of saidfront unit switches are assigned an output port number and each of saidn input ports of said rear unit switches are assigned an input portnumber; and wherein the input port numbers of said front unit switchesare reassigned in accordance with the following formula, and the outputport numbers of said rear unit switches are assigned in sequence fromthe uppermost position to the lowermost position:(i,j)=Xn+Y, whereinXn={jquo2+n/{2{imod2}}}, and Y={iquo2+n/{2{imod2}}}, and i correspondsto a number of row, and j corresponds to a number of column, and "iquo2"denotes the quotient of "i" divided by 2, and "imod2" denotes theremainder of "i" divided by 2, and "jquo2" denotes the quotient of "j"divided by 2, and "jmod2" denotes the remainder of "j" divided by
 2. 14.The network of claim 13, with the network being in an asynchronoustransfer mode on basis of a Banyan network.
 15. The network of claim 13,wherein N is greater than n.
 16. The network of claim 13, wherein N isequal to n multiplied by n.
 17. The network of claim 13, wherein thenetwork is of three dimensional structure.
 18. The network of claim 13,wherein the switching network is formed on one printed circuit board.19. The network of claim 14, wherein the switching network is formed onone printed circuit board.